This invention relates to improvements in manually actuated impact tools for applying a torsional force, greater than that applied manually to the tool, to threaded-type fastenings, such as tools of the type shown in U.S. Pat. Nos. 2,661,647, 2,844,982, 3,156,309, and particularly U.S. Pat. Nos. 2,954,714, hereinafter referred to as patent No. 1; and 3,108,506, hereinafter referred to as patent No. 2. Each of these patents, in common with the present application, shows a manually operable impact tool utilizing a manually operable handle, a main power spring, and an annular inertia member carrying pawls which engage a ratchet-toothed member with an output shaft to produce, from energy derived from movement of the handle by torque applied thereto by the operator and stored in and later released by the spring, successive impacts which are delivered as torque through the output shaft to a threaded fastener such as a bolt or nut to tighten or loosen it, when the pawls, disengaged from their respective ratchet teeth on angular movement of the handle relative to the inertia member, engage their respective successive ratchet teeth and release thereto as impact energy the energy stored in the spring and conveyed to the pawls by the inertia member, to result in a magnitude of torque delivered to the output shaft, and through it to the threaded fastener, substantially greater than that of the torque applied to the handle by the operator.
While impact tools constructed in accordance with the disclosures of patents No. 1 and No. 2 have proven superior to those constructed in accordance with the other patents listed above and have found advantageous uses in industry for several years, the experience gained in these uses has disclosed a number of deficiencies in their design and construction. The general objectives of this invention are to eliminate these deficiencies and to provide additional improvements to the former designs and constructions.